Diffuser pipes are provided in certain gas turbine engines for directing flow of compressed air from an impeller of a centrifugal compressor to an annular chamber containing the combustor, while diffusing the high speed air. These diffuser pipes are typically circumferentially arranged around a periphery of the impeller, and are designed to transform kinetic energy of the flow into pressure energy. Diffuser pipes may provide a uniform exit flow with minimal distortion, because this is preferable for flame stability, low combustor loss, reduced hot spots etc.
While longer diffuser pipes may accomplish better flow diffusion, spatial constraints of the gas turbine engine may restrict the possible practical length of such diffuser pipes. Large flow diffusion in diffuser pipes over insufficient pipe length may result in thick and weak boundary layer buildup on the wall of the diffuser pipe. To compensate for a shorter length, many diffuser pipes have a tight bend formed along their length. Turbulence and other non-streamline behavior of the flow at the bend may however lead to pressure losses and decreased efficiency of the diffuser pipe, and therefore of the compressor.